Backlight value adjusting method and system

Abstract

The invention relates to the technical field of backlight dimming, in particular to a backlight value adjusting method and system, and the method comprises the steps: obtaining an image to be subjected to backlight dimming, converting the image to be subjected to backlight dimming into a grayscale image, and dividing the grayscale image based on the mean value and variance of the grayscale image to obtain two demarcation points; and partitioning the grayscale image based on the two demarcation points to obtain different regions corresponding to the grayscale image, the different regions including a first region, a second region and a third region. According to the invention, the grayscale image is divided into different areas, and the backlight brightness is respectively adjusted according to the characteristics of each area, so that the regionalized adjustment can better adapt to the distribution of the image content, the contrast and layering of the image can be improved, and the details of the image can be displayed more clearly.

Description

Technical Field

[0001] The present invention relates to the technical field of backlight dimming, and in particular to a backlight value adjustment method and a system thereof. Background Art

[0002] Backlight value adjustment refers to the operation of adjusting the luminous intensity of the backlight source behind the display device (such as LCD monitors, LCD TVs, etc.). The backlight source provides light behind the screen, and its luminous intensity directly affects the overall brightness and display effect of the screen.

[0003] Traditional methods usually use a unified backlight adjustment method and do not perform zoning processing based on image content. This means that no matter how the brightness differences in different areas of the image are, the backlight is adjusted as a whole, thereby reducing the overall display quality of the image. Traditional methods rarely build a matrix based on the backlight brightness and compensate for the LCD pixels. Since there is no such LCD pixel compensation mechanism for backlight conditions, when faced with uneven backlight or mismatch between the backlight and the LCD pixel response, problems such as light leakage and color deviation are prone to occur. Moreover, traditional methods do not distinguish between brightness differences in image content areas for backlight adjustment. When the dark tone area accounts for a large proportion of the displayed image, the overall backlight brightness is still maintained at a high level. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the disadvantages of the above-mentioned prior art and provide a backlight value adjustment method and system thereof.

[0005] The technical solution adopted to solve the above technical problem is: a backlight value adjustment method, comprising: Acquire an image to be backlight dimmed, convert the image to be backlight dimmed into a grayscale image, and divide the grayscale image based on a mean and a variance of the grayscale image to obtain two dividing points; Partitioning the grayscale image based on the two dividing points to obtain different regions corresponding to the grayscale image, wherein the different regions include a first region, a second region, and a third region; Acquire backlight dimming grayscales of different areas based on grayscale histograms of different areas corresponding to the grayscale images, calculate backlight brightness of different areas based on the backlight dimming grayscales of different areas, and calculate backlight dimming ratios of different areas based on the backlight brightness of different areas; Generating a pulse width modulation signal of a corresponding target screen based on the backlight dimming ratios of the different areas, and adjusting the brightness of a backlight unit of the target screen based on the pulse width modulation signal; A backlight brightness matrix is ​​constructed based on the backlight brightness of the different areas, the backlight brightness matrix is ​​smoothed to obtain a standard backlight brightness matrix, and the liquid crystal pixels of the target screen are compensated based on the standard backlight brightness matrix.

[0006] Preferably, the grayscale image is obtained based on the largest component of the three components R, G, and B of each pixel in the image to be backlight dimmed, wherein the expression for converting the image to be backlight dimmed into the grayscale image is as follows: ; in, Indicates that each pixel in the backlight dimming image has a coordinate of The largest component among the three components of R, G, and B, , and Indicates that each pixel in the backlight dimming image has a coordinate of The R, G, and B components of Indicates the pixel coordinates of the image to be dimmed and the grayscale image.

[0007] Preferably, dividing the grayscale image based on the mean and variance of the grayscale image to obtain two dividing points includes: The mean and variance of the grayscale image are calculated, wherein the calculation formulas for the mean and variance of the grayscale image are as follows: ; in, represents the mean value of the grayscale image, represents the variance of the grayscale image, Represents a grayscale image at coordinates The pixel value of and Represent the length and width of the grayscale image respectively; The grayscale image is demarcated based on the mean and variance of the grayscale image to obtain two demarcation points, wherein the expressions of the two demarcation points are as follows: ; in, Represents the first dividing point of the grayscale image, Indicates the second dividing point of the grayscale image.

[0008] Preferably, the first area is a low brightness area, the second area is a medium brightness area, and the third area is a high brightness area.

[0009] Preferably, obtaining the backlight dimming grayscale levels of the different areas based on the grayscale histograms of the different areas corresponding to the grayscale image includes: Obtaining grayscale histograms of different areas corresponding to the grayscale image; Obtaining an adaptive threshold of the image content of the different regions based on a maximum inter-class variance method, wherein the adaptive threshold is a threshold that maximizes the inter-class variance of the different regions; Binarizing each pixel in the different regions based on the adaptive threshold to obtain a binary image; Counting the number of points whose pixel values ​​are 1 in different regions of the binary image, and counting the number of points whose pixel values ​​are 0 in different regions of the binary image; The backlight coefficients of different regions are calculated based on the number of points whose pixel values ​​are 1 and 0 in different regions of the binary image, wherein the calculation formula of the backlight coefficient is as follows: ; in, The coordinates of the region corresponding to the binary image are The backlight factor, Indicates the number of points with pixel value 1 in different areas of the binary image. Indicates the number of points with pixel values ​​of 0 in different areas of the binary image; The backlight dimming grayscales of the different regions are calculated based on the backlight coefficients of the different regions. The calculation formulas for the backlight dimming grayscales of the different regions are as follows: ; in, The coordinates of the region corresponding to the binary image are Backlight dimming grayscale, and Indicates the length and width of different areas.

[0010] Preferably, the calculation formula of the backlight brightness is as follows: ; in, The coordinates of the region corresponding to the binary image are Backlight brightness, The coordinates of the region corresponding to the binary image are The maximum gray value of The coordinates of the region corresponding to the binary image are The average gray value.

[0011] Preferably, the calculation formula of the backlight dimming ratio is as follows: ; in, The coordinates of the region corresponding to the binary image are Backlight dimming ratio, and Indicates the preset adjustment parameters.

[0012] Preferably, the compensation of the liquid crystal pixels of the target screen includes linear compensation and nonlinear compensation, wherein the expression of the linear compensation is as follows: ; in, Represents the coordinates The pixel value after linear compensation of the pixel, Represents the coordinates The pixel value before linear compensation of the pixel, Indicates the backlight brightness when the backlight is fully on. Indicates that the coordinates after backlight smoothing are The backlight brightness of the pixel.

[0013] Preferably, the expression of the nonlinear compensation is as follows: ; in, Represents the coordinates The pixel value after nonlinear compensation of the pixel, Represents the coordinates The pixel value before nonlinear compensation of the pixel, Indicates the correction factor of the target screen.

[0014] The technical solution adopted to solve the above technical problem is: a backlight value adjustment system, which is applicable to the backlight value adjustment method described above, comprising: An image processing unit, the image processing unit is used to obtain the image to be backlight dimmed, convert the image to be backlight dimmed into a grayscale image, and demarcate the grayscale image based on the mean and variance of the grayscale image to obtain two demarcation points; An image partitioning unit, the image partitioning unit is used to partition the grayscale image based on the two dividing points to obtain different regions corresponding to the grayscale image, wherein the different regions include a first region, a second region and a third region; A backlight dimming unit, the backlight dimming unit is used to obtain backlight dimming grayscale levels of different areas based on grayscale histograms of different areas corresponding to the grayscale image, calculate backlight brightness of the different areas based on the backlight dimming grayscale levels of the different areas, and calculate backlight dimming ratios of the different areas based on the backlight brightness of the different areas; A brightness adjustment unit, the brightness adjustment unit is used to generate a pulse width modulation signal of a corresponding target screen based on the backlight dimming ratios of the different areas, and to adjust the brightness of the backlight unit of the target screen based on the pulse width modulation signal; A pixel compensation unit is used to construct a backlight brightness matrix based on the backlight brightness of the different areas, smooth the backlight brightness matrix to obtain a standard backlight brightness matrix, and compensate the liquid crystal pixels of the target screen based on the standard backlight brightness matrix.

[0015] The beneficial effects of the present invention are as follows: (1) The present invention divides the grayscale image into different regions and adjusts the backlight brightness according to the characteristics of each region. This regionalized adjustment can better adapt to the distribution of image content, improve the contrast and layering of the image, and make the details of the image more clearly displayed; (2) The present invention constructs and smoothes the backlight brightness matrix, and then compensates the liquid crystal pixels according to the standard backlight brightness matrix, which helps to overcome some display defects that may exist in the liquid crystal display itself, thereby further improving the display clarity and color accuracy of the image; (3) The present invention reduces energy consumption by adjusting the backlight brightness according to the actual needs of different regions of the image, especially for mobile devices, it can effectively extend the battery life, and the entire backlight value adjustment method is based on the content of the image to be dimmed. Whether it is a static image or a dynamic video picture, it can be adaptively adjusted according to the specific brightness distribution and characteristics of the picture. This adaptive adjustment enables users to obtain a more comfortable and realistic visual experience when watching different types of images or videos. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic flow chart of the steps of an overall method in an embodiment of the present invention; Figure 2 A schematic diagram of the system architecture of an overall system in an embodiment of the present invention.

[0017] Figure numerals: 1. Image processing unit; 2. Image partitioning unit; 3. Backlight dimming unit; 4. Brightness adjustment unit; 5. Pixel compensation unit. DETAILED DESCRIPTION

[0018] Embodiment 1, as Figure 1 As shown, a backlight value adjustment method proposed by the present invention includes: S1, obtaining an image to be backlight dimmed, converting the image to be backlight dimmed into a grayscale image, and dividing the grayscale image based on the mean and variance of the grayscale image to obtain two dividing points; S2. Partitioning the grayscale image based on two dividing points to obtain different regions corresponding to the grayscale image, wherein the different regions include a first region, a second region, and a third region; S3, obtaining backlight dimming grayscale levels of different areas based on grayscale histograms of different areas corresponding to the grayscale images, calculating backlight brightness of different areas based on the backlight dimming grayscale levels of different areas, and calculating backlight dimming ratios of different areas based on the backlight brightness of different areas; S4, generating a pulse width modulation signal of a corresponding target screen based on the backlight dimming ratios of different areas, and adjusting the brightness of a backlight unit of the target screen based on the pulse width modulation signal; S5. Construct a backlight brightness matrix based on the backlight brightness of different areas, smooth the backlight brightness matrix to obtain a standard backlight brightness matrix, and compensate the liquid crystal pixels of the target screen based on the standard backlight brightness matrix.

[0019] In the present invention, the image to be backlight-dimmed refers to an original image that needs to be subjected to a backlight adjustment operation. In display devices (such as liquid crystal displays, etc.), in order to make the image displayed on the screen clearer, with better visual effects and energy saving, the backlight value needs to be adjusted according to the content of the image. The original image that will be used to adjust the backlight related parameters is called the backlight dimming image; a grayscale image is an image that only contains brightness information. Each pixel uses only one value to represent its brightness, unlike a color image that requires multiple components (such as RGB three components) to represent the color. The range of this value is usually 0 (indicating black) to 255 (indicating white), and the middle value represents different degrees of gray. Converting a color image to a grayscale image is a step in adjusting the backlight value, which can simplify the subsequent analysis of the image brightness characteristics; the demarcation point is when the grayscale image is demarcated according to the mean and variance of the grayscale image. The demarcation point is the key point for dividing different areas of the image. By determining the demarcation point by the mean and variance, the image can be divided into different parts according to the brightness characteristics, preparing for the subsequent partition backlight adjustment; the backlight dimming grayscale refers to the actual luminous intensity of the screen backlight source, which directly affects the display brightness of the screen. By calculating the backlight brightness of different areas according to the backlight dimming grayscale of different areas, the brightness of different areas of the screen can be adjusted differently according to the image content; the backlight dimming ratio is a numerical value used to represent the proportional relationship between the backlight brightness of different areas. The backlight dimming ratio is calculated based on the backlight brightness of different areas, and the relative backlight adjustment amplitude of each area can be determined; the pulse width modulation signal is a digital signal that controls the level of the analog signal by changing the width (duty cycle) of the pulse. In the screen backlight adjustment, the corresponding PWM signal is generated based on the backlight dimming ratio of different areas, and the brightness of the target screen backlight unit is adjusted by changing the duty cycle of the PWM signal. When the duty cycle of the PWM signal is high, the average brightness of the backlight unit is high; when the duty cycle is low, the average brightness is low; the target screen refers to the screen that is ultimately to be backlight adjusted, and its backlight unit is a component located behind the screen, responsible for providing the light source behind the screen; liquid crystal pixel compensation is an operation used to improve the display quality of the screen. A backlight brightness matrix is ​​constructed based on the backlight brightness of different areas, and then a standard backlight brightness matrix is ​​obtained through smoothing. The standard backlight brightness matrix is ​​then used to compensate the liquid crystal pixels of the target screen.

[0020] Embodiment 2, a backlight value adjustment method proposed by the present invention, compared with embodiment 1, this embodiment also includes: a grayscale image is obtained based on the largest component of the three components R, G, and B of each pixel in the backlight dimming image, wherein the expression for converting the backlight dimming image into the grayscale image is as follows: ; in, Indicates that each pixel in the backlight dimming image has a coordinate of The largest component among the three components of R, G, and B, , and Indicates that each pixel in the backlight dimming image has a coordinate of The R, G, and B components of Indicates the pixel coordinates of the image to be backlight dimmed or the grayscale image.

[0021] It should be noted that grayscale images only contain brightness information, removing the complexity of color information, which makes subsequent image processing simpler and more efficient. There is no need to consider the differences and mutual influence of different color channels, and we can focus on adjusting the brightness, reducing the amount of calculation and processing difficulty.

[0022] In an optional embodiment, the grayscale image is demarcated based on the mean and variance of the grayscale image to obtain two demarcation points, including: A1. Calculate the mean and variance of the grayscale image. The calculation formulas for the mean and variance of the grayscale image are as follows: ; in, represents the mean value of the grayscale image, represents the variance of the grayscale image, Represents a grayscale image at coordinates The pixel value of and Represent the length and width of the grayscale image respectively; A2. Demarcate the grayscale image based on the mean and variance of the grayscale image to obtain two demarcation points, where the expressions of the two demarcation points are as follows: ; in, Represents the first dividing point of the grayscale image, Indicates the second dividing point of the grayscale image.

[0023] It should be noted that the grayscale image is partitioned based on the dividing points, and different areas are clearly divided, such as the first area, the second area, and the third area. This enables areas with different brightness ranges to be processed separately and in a targeted manner, thereby avoiding problems such as local detail loss or overall uneven brightness that may be caused by unified adjustment of the entire image, and helps to achieve a more refined backlight dimming effect.

[0024] In an optional embodiment, the first area is a low brightness area, the second area is a medium brightness area, and the third area is a high brightness area.

[0025] In an optional embodiment, obtaining backlight dimming grayscale levels of different areas based on grayscale histograms of different areas corresponding to the grayscale image includes: B1, obtaining grayscale histograms of different areas corresponding to the grayscale image; B2. Obtaining adaptive thresholds of image contents in different regions based on the maximum inter-class variance method, wherein the adaptive threshold is a threshold that maximizes the inter-class variance of different regions; B3, binarizing each pixel in different regions based on an adaptive threshold to obtain a binary image; B4, counting the number of points whose pixel values ​​are 1 in different regions of the binary image, and counting the number of points whose pixel values ​​are 0 in different regions of the binary image; B5. Calculate the backlight coefficient of different areas based on the number of points with pixel values ​​of 1 and 0 in different areas of the binary image, where the calculation formula of the backlight coefficient is as follows: ; in, The coordinates of the region corresponding to the binary image are The backlight factor, Indicates the number of points with pixel value 1 in different areas of the binary image. Indicates the number of points with pixel values ​​of 0 in different areas of the binary image; B6. The backlight dimming grayscale of different areas is calculated based on the backlight coefficient of different areas. The calculation formula of the backlight dimming grayscale of different areas is as follows: ; in, The coordinates of the region corresponding to the binary image are Backlight dimming grayscale, and Indicates the length and width of different areas.

[0026] It should be noted that obtaining the backlight dimming grayscale based on the grayscale histogram of different areas can accurately reflect the brightness characteristics of each area, so as to calculate the backlight brightness and dimming ratio. In this way, personalized dimming settings can be made according to the actual brightness conditions of different areas, so that each area can achieve the ideal backlight brightness, improve the display quality and visual effects of the entire screen, and avoid local overbrightness or overdarkness.

[0027] In an optional embodiment, the calculation formula of the backlight brightness is as follows: ; in, The coordinates of the region corresponding to the binary image are Backlight brightness, The coordinates of the region corresponding to the binary image are The maximum gray value of The coordinates of the region corresponding to the binary image are The average gray value.

[0028] In an optional embodiment, the backlight dimming ratio is calculated as follows: ; in, The coordinates of the region corresponding to the binary image are Backlight dimming ratio, and Indicates the preset adjustment parameters.

[0029] In an optional embodiment, the compensation of the liquid crystal pixels of the target screen includes linear compensation and nonlinear compensation, wherein the expression of the linear compensation is as follows: ; in, Represents the coordinates The pixel value after linear compensation of the pixel, Represents the coordinates The pixel value before linear compensation of the pixel, Indicates the backlight brightness when the backlight is fully on. Indicates that the coordinates after backlight smoothing are The backlight brightness of the pixel.

[0030] In an optional embodiment, the expression of nonlinear compensation is as follows: ; in, Represents the coordinates The pixel value after nonlinear compensation of the pixel, Represents the coordinates The pixel value before nonlinear compensation of the pixel, Indicates the correction factor of the target screen.

[0031] Embodiment three, as Figure 2 As shown, a backlight value adjustment system proposed by the present invention is applicable to the backlight value adjustment method described above, comprising: An image processing unit 1 is used to obtain an image to be backlight dimmed, convert the image to be backlight dimmed into a grayscale image, and divide the grayscale image based on a mean and a variance of the grayscale image to obtain two dividing points; An image partitioning unit 2, the image partitioning unit 2 is used to partition the grayscale image based on two dividing points to obtain different regions corresponding to the grayscale image, wherein the different regions include a first region, a second region and a third region; A backlight dimming unit 3, which is used to obtain backlight dimming grayscale levels of different areas based on grayscale histograms of different areas corresponding to the grayscale image, calculate backlight brightness of different areas based on the backlight dimming grayscale levels of different areas, and calculate backlight dimming ratios of different areas based on the backlight brightness of different areas; A brightness adjustment unit 4, which is used to generate a pulse width modulation signal of a corresponding target screen based on the backlight dimming ratio of different areas, and to adjust the brightness of the backlight unit of the target screen based on the pulse width modulation signal; The pixel compensation unit 5 is used to construct a backlight brightness matrix based on the backlight brightness of different areas, smooth the backlight brightness matrix to obtain a standard backlight brightness matrix, and compensate the liquid crystal pixels of the target screen based on the standard backlight brightness matrix.

[0032] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A backlight value adjustment method, characterized in that: include: Acquire an image to be backlight dimmed, convert the image to be backlight dimmed into a grayscale image, and divide the grayscale image based on a mean and a variance of the grayscale image to obtain two dividing points; Partitioning the grayscale image based on the two dividing points to obtain different regions corresponding to the grayscale image, wherein the different regions include a first region, a second region, and a third region; Acquire backlight dimming grayscales of different areas based on grayscale histograms of different areas corresponding to the grayscale images, calculate backlight brightness of different areas based on the backlight dimming grayscales of different areas, and calculate backlight dimming ratios of different areas based on the backlight brightness of different areas; Generating a pulse width modulation signal of a corresponding target screen based on the backlight dimming ratios of the different areas, and adjusting the brightness of a backlight unit of the target screen based on the pulse width modulation signal; A backlight brightness matrix is ​​constructed based on the backlight brightness of the different areas, the backlight brightness matrix is ​​smoothed to obtain a standard backlight brightness matrix, and the liquid crystal pixels of the target screen are compensated based on the standard backlight brightness matrix.

2. A backlight value adjustment method according to claim 1, characterized in that: The grayscale image is obtained based on the largest component of the three components R, G, and B of each pixel in the backlight dimming image, wherein the expression for converting the backlight dimming image into the grayscale image is as follows: ； in, Indicates that each pixel in the backlight dimming image has a coordinate of The largest component among the three components of R, G, and B, , and Respectively represent each pixel point in the backlight dimming image at the coordinates The R, G, and B components of Indicates the pixel coordinates of the image to be backlight dimmed or the grayscale image.

3. A backlight value adjustment method according to claim 2, characterized in that: The grayscale image is demarcated based on the mean and variance of the grayscale image to obtain two demarcation points, including: The mean and variance of the grayscale image are calculated, wherein the calculation formulas for the mean and variance of the grayscale image are as follows: ； in, represents the mean value of the grayscale image, represents the variance of the grayscale image, Represents a grayscale image at coordinates The pixel value of and Represent the length and width of the grayscale image respectively; The grayscale image is demarcated based on the mean and variance of the grayscale image to obtain two demarcation points, wherein the expressions of the two demarcation points are as follows: ； in, Represents the first dividing point of the grayscale image, Indicates the second dividing point of the grayscale image.

4. A backlight value adjustment method according to claim 3, characterized in that: The first area is a low brightness area, the second area is a medium brightness area, and the third area is a high brightness area.

5. A backlight value adjustment method according to claim 4, characterized in that: Acquiring backlight dimming grayscale levels of different areas based on grayscale histograms of different areas corresponding to the grayscale image, including: Obtaining grayscale histograms of different areas corresponding to the grayscale image; Obtaining an adaptive threshold of the image content of the different regions based on a maximum inter-class variance method, wherein the adaptive threshold is a threshold that maximizes the inter-class variance of the different regions; Binarizing each pixel in the different regions based on the adaptive threshold to obtain a binary image; Counting the number of points whose pixel values ​​are 1 in different regions of the binary image, and counting the number of points whose pixel values ​​are 0 in different regions of the binary image; The backlight coefficients of different regions are calculated based on the number of points whose pixel values ​​are 1 and 0 in different regions of the binary image, wherein the calculation formula of the backlight coefficient is as follows: ； in, The coordinates of the region corresponding to the binary image are The backlight factor, Indicates the number of points with pixel value 1 in different areas of the binary image. Indicates the number of points with pixel values ​​of 0 in different areas of the binary image; The backlight dimming grayscales of the different regions are calculated based on the backlight coefficients of the different regions. The calculation formulas for the backlight dimming grayscales of the different regions are as follows: ； in, The coordinates of the region corresponding to the binary image are Backlight dimming grayscale, and Indicates the length and width of different areas.

6. The backlight value adjustment method according to claim 5, characterized in that: The calculation formula of the backlight brightness is as follows: ; in, The coordinates of the region corresponding to the binary image are Backlight brightness, The coordinates of the region corresponding to the binary image are The maximum gray value of The coordinates of the region corresponding to the binary image are The average gray value.

7. A backlight value adjustment method according to claim 6, characterized in that: The calculation formula of the backlight dimming ratio is as follows: ； in, The coordinates of the region corresponding to the binary image are Backlight dimming ratio, and Indicates the preset adjustment parameters.

8. The backlight value adjustment method according to claim 6, characterized in that: The compensation of the liquid crystal pixels of the target screen includes linear compensation and nonlinear compensation, wherein the expression of the linear compensation is as follows: ; in, Represents the coordinates The pixel value after linear compensation of the pixel, Represents the coordinates The pixel value before linear compensation of the pixel, Indicates the backlight brightness when the backlight is fully on. Indicates that the coordinates after backlight smoothing are The backlight brightness of the pixel.

9. The backlight value adjustment method according to claim 8, characterized in that: The expression of the nonlinear compensation is as follows: ； in, Represents the coordinates The pixel value after nonlinear compensation of the pixel, Represents the coordinates The pixel value before nonlinear compensation of the pixel, Indicates the correction factor of the target screen.

10. A backlight value adjustment system, applied to a backlight value adjustment method as claimed in any one of claims 1 to 9, characterized in that: include: An image processing unit (1), the image processing unit (1) being used to obtain an image to be backlight dimmed, convert the image to be backlight dimmed into a grayscale image, and divide the grayscale image based on a mean and a variance of the grayscale image to obtain two dividing points; An image partitioning unit (2), the image partitioning unit (2) being used to partition the grayscale image based on the two dividing points to obtain different regions corresponding to the grayscale image, wherein the different regions include a first region, a second region and a third region; A backlight dimming unit (3), the backlight dimming unit (3) being used for obtaining backlight dimming grayscale levels of different areas based on grayscale histograms of different areas corresponding to the grayscale image, calculating backlight brightness of the different areas based on the backlight dimming grayscale levels of the different areas, and calculating backlight dimming ratios of the different areas based on the backlight brightness of the different areas; A brightness adjustment unit (4), the brightness adjustment unit (4) being used to generate a pulse width modulation signal of a corresponding target screen based on the backlight dimming ratios of the different areas, and to adjust the brightness of the backlight unit of the target screen based on the pulse width modulation signal; A pixel compensation unit (5), the pixel compensation unit (5) being used to construct a backlight brightness matrix based on the backlight brightness of the different areas, to smooth the backlight brightness matrix to obtain a standard backlight brightness matrix, and to compensate the liquid crystal pixels of the target screen based on the standard backlight brightness matrix.

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